They have a 7 day free trial. It's worth a look. Coincidentally, I just decided against continuing my subscription with Sling on Monday after 6 days of the trial. The quality of the video was fine. The price was fine. There were a few hang ups that I just couldn't get over.
1. Most of the content my family would want to watch was on the orange tier, and all of that is confined to a single stream. So if I'm downstairs watching a football game on ESPN my wife cannot be upstairs watching a show simultaneously on HGTV.
2. No DVR capability
3. It still seems very hodge-podgy. Some channels you can rewind, some you can't. There's no real rhyme or reason about which ones can and cannot. Some local channels are available in some markets, some are not (I could personally only get Fox).
Would have saved my family about $60/month over what we have now with DirecTV if we went with Sling and took the orange, blue and sports package. But it just felt a little too half baked at the moment. Just doing a little research on the service it sounds like it has matured a good bit since it started last year, so hopefully it will continue to get better and it, or some other streaming option, will become good enough to get rid of the packaged cable/satellite subscriptions.
Sling does indeed allow multiple people to be streaming at the same time. Im watching in my room while my girlfriend is in living room watching right now, soooo, not sure why you think you cant do that. Possibly they dont allow on free trial but you can for sure do it.